Smart materials that monitor and respond to changing conditions have a wide range of practical applications. For example, pharmaceuticals or drugs encapsulated within biodegradable polymers may be used to yield controlled release functionality. In other examples, drugs encapsulated within soluble polymers achieve similar results, i.e. being responsive to the surrounding environment. However, these methods have not found wide application with engineered fibrous structures, such as nonwovens and other textiles, in part because of polymer-to-process compatibility limitations. Thus, smart fabrics engineered from fibrous materials have been elusive.
Nonwoven fabrics are typically formed directly from fibers (i.e. staple fibers) or polymers. Fabric formation directly from polymers is referred to as direct spinning and includes either melt spinning a thermoplastic polymer or solution spinning Direct spinning, however, typically yields larger fiber diameters, e.g. 30 to 40 microns and higher. In addition, a limited number of polymers, and blends of polymers, are compatible with direct spinning methods. While the direct spinning methods are amenable to varied fiber diameter or shapes, complex equipment configurations and additional processing are required.